"She adored that boy. He was the love of her life."
Lisa has previously spoken of her son's similarity to her dad Elvis, calling it "uncanny".
She said: "Ben does look so much like Elvis. Everybody was grabbing him for a photo because it is just uncanny."
In 2009 Benjamin was reported to have signed a US$5million record deal with Universal.
"The music will be nothing like Elvis, nothing like him at all," he said in an interview at the time.
The most recent photo of Benjamin on his mother's Instagram account was posted in June of last year: It shows Lisa Marie with her two older children, Benjamin and Riley, alongside her younger twin daughters from her fourth marriage, to guitarist Michael Lockwood.
"Mama lion with cubs," she captioned the sweet family pic.
Lisa Marie was born to Elvis and Priscilla Presley on February 1, 1968.
Her parents were married on May 1, 1967, at the Aladdin Hotel in Las Vegas. They divorced in 1973.
Lisa Marie and her first husband, Keough, had two children together, Benjamin and his sister, the actress Riley Keough. The couple were married on October 3, 1988 and divorced on May 6, 1994.
Twenty days later Lisa Marie married Michael Jackson. In 1996, citing irreconcilable differences, she filed for divorce.
She also had a third marriage to Nicolas Cage that lasted two months in 2002.
In January it was reported Lisa, 51, and her ex-husband Michael Lockwood have been engaged in a nasty custody battle over their 11-year-old twin daughters, Finley and Harper.
Lisa was married to Lockwood, her fourth husband, in 2006, and she gave birth to their twin girls in October 2008.
She had her two older children, Benjamin and his sister, the actress Riley Keough with her first husband, musician Danny Keough.
WHERE TO GET HELP:
If you are worried about your or someone else's mental health, the best place to get help is your GP or local mental health provider. However, if you or someone else is in danger or endangering others, call police immediately on 111.
OR IF YOU NEED TO TALK TO SOMEONE ELSE:
• 0800 543 354 (0800 LIFELINE) or free text 4357 (HELP) (available 24/7)
• https://www.lifeline.org.nz/services/suicide-crisis-helpline
• YOUTHLINE: 0800 376 633
• NEED TO TALK? Free call or text 1737 (available 24/7)
• KIDSLINE: 0800 543 754 (available 24/7)
• WHATSUP: 0800 942 8787 (1pm to 11pm)
• DEPRESSION HELPLINE: 0800 111 757 or TEXT 4202
• NATIONAL ANXIETY 24 HR HELPLINE: 0800 269 4389
